The present invention relates to a system for detecting the disengagement of a joint portion provided in a feedback path for blowby gas.
The blowby gas is generated when the mixture gas of the fuel and the air leaks from a portion between the cylinder and the piston of an engine. For example, in the engine for an automobile, the blow by gas is collected and fed back to an intake path of the engine so as to prevent the blowby gas from being emitted in the atmosphere.
When performing the maintenance of the engine room of an automobile, a pipe for feeding back the blowby gas is sometimes removed or disengaged.
However, in the prior art, even when the pipe is kept in the disengaged state, the engine operates and an alarm indication etc. for notifying the removal or disengagement of the pipe is not made. Thus, there may arise such a matter that a driver operates the engine without noticing that the pipe is disengaged thereby to emit the blowby gas in the atmosphere.
Accordingly, the invention has been made in view of the aforesaid problem of the prior art, and an object of the invention is to provide a disengagement detection system for a joint portion which can detect the disengagement of the joint portion provided at a feedback path for blowby gas.
A disengagement detection system for a joint portion according to aspect 1 is arranged in a manner that in the disengagement detection system wherein a feedback path for deeding back blowby gas to an intake path of an engine is formed by coupling a plurality of cavities, the disengagement detection system is characterized in that
joint portions provided at each of a pair of the cavities and mutually coupled are provided with a pair of connector portions which are engaged/disengaged in accordance with engagement/disengagement of the joint portions, respectively,
a detection means is provided for detecting a non-conduction state between terminal metal members provided at the connector portions, and
the detection means outputs a disengagement detection signal when a state between the terminal metal members is non-conductive.
The invention as in aspect 2 is characterized in that in the disengagement detection system for a joint portion according to aspect 1,
plural pairs of the connector portions are provided,
the detection means includes a switch circuit which is closed only when all the connector portions are coupled to partner-side connector portions, respectively, and all the terminal metal members are conductively coupled mutually, and
the detection means detects that a state between the terminal metal members having been mutually coupled at one of the connector portions becomes non-conductive when the switch circuit is opened.
The invention as in aspect 3 is characterized in that in the disengagement detection system for a joint portion according to aspect 2,
the cavity having two the connector portions is provided with a pair of electric paths for connecting, between the two connector portions, the pair of terminal metal members provided at the two connector portions, and
the pair of electric paths are arranged to flow currents in opposite direction when sad switch circuit is closed.
According to the arrangement of aspect 1, when the joint portion is disengaged, the connector portion is also disengaged, so that the state between the terminal metal members provided at the connector portions becomes non-conductive. The detection means detects such a non-conductive state thereby to output the disengagement detection signal. Thus, a diver can notice that the joint portion is disengaged.
According to the arrangement of aspect 2, in the case where a plurality of the joint portions are provided at the feedback path for the blowby gas, when even one of the joint portions is disengaged, the switch circuit is opened. Thus, the disengagement of the joint portion can be detected.
According to the arrangement of aspect 3, currents flow in opposite direction in the pair of the electric paths provided in the cavity to constitute outward and homeward paths of the switch circuit, respectively. Thus, the configuration of the switch circuit along the cavity can be simplified as compared with the case where only the outward path is provided between the connector portions provided at the cavity and the homeward path is provided in another portion.